An echo canceler is generally configured as a combination of a linear echo processing unit for canceling a linear echo component and a residual echo suppression processing unit for suppressing the linear echo component that cannot be canceled out by the linear echo processing and a nonlinear echo component. Such a configuration is disclosed in Non-Patent Document 1, for example. The echo canceler disclosed in the Non-Patent Document 1, however, has a problem in that when an echo and send voice overlap each other, that is, when double talk occurs, the residual echo suppression processing unit suppresses both the residual echo and send voice.
To solve the foregoing problem, Patent Document 1, for example, discloses a method of flexibly controlling suppression coefficients used for the amplitude suppression of a voice signal in the residual echo suppression processing unit. The Patent Document 1 discloses an echo suppression method for obtaining an echo suppression quantity using the power of an estimated echo signal obtained by multiplying the received signal power by the amount of acoustic coupling of an echo path, which is estimated from the power of a microphone input signal on which the send voice and echo signal are superposed.